Search Publications
The first photometric analysis of the totally eclipsing contact binary V811 Cep
Li, Kai; Gao, Xing; Liu, Yuan +1 more
The first photometric analysis of V811 Cep was carried out. The first complete light curves of V, R and I bands are given. The analysis was carried out by the Wilson-Devinney (W-D) program, and the results show that V811 Cep is a median-contact binary (f = 33.9(±4.9)%) with a mass ratio of 0.285. It is a W-subtype contact binary, that is, the comp…
Constraints on the dust extinction law of the Galaxy with Swift/UVOT, Gaia, and 2MASS
Cropper, Mark; Charlot, Stéphane; Kawata, Daisuke +6 more
We explore variations of the dust extinction law of the Milky Way by selecting stars from the Swift/UVOT Serendipitous Source Catalogue, cross-matched with Gaia DR2 and 2MASS to produce a sample of 10 452 stars out to ~4 kpc with photometry covering a wide spectral window. The near ultraviolet passbands optimally encompass the 2175 Å bump, so that…
Similarities of magnetoconvection in the umbra and in the penumbra of sunspots
Solanki, S. K.; Lagg, A.; Löptien, B. +1 more
Context. It is unclear why there is a rather sharp boundary in sunspots between the umbra and the penumbra. Both regions exhibit magnetoconvection, which manifests in penumbral filaments in the penumbra and in umbral dots in the umbra.
Aims: Here we compare the physical properties of umbral dots and penumbral filaments. Our goal is to underst…
Ancient and present surface evolution processes in the Ash region of comet 67P/Churyumov-Gerasimenko
Jorda, L.; Groussin, O.; Bouley, S. +3 more
Aims: The Rosetta mission provided us with detailed data of the surface of the nucleus of comet 67P/Churyumov-Gerasimenko. In order to better understand the physical processes associated with the comet activity and the surface evolution of its nucleus, we performed a detailed comparative morphometrical analysis of two depressions located in t…
Revealing Ionization Conditions of Sz 102 with Spatially Resolved [Ne III] Microjets
Herczeg, Gregory J.; Liu, Chun-Fan; Shang, Hsien +1 more
Forbidden neon emission lines from small-scale microjets can probe high-energy processes in low-mass young stellar systems. We obtained spatially resolved [Ne III] spectra in the microjets from the classical T Tauri Star Sz 102 using the Hubble Space Telescope Imaging Spectrograph at a spatial resolution of ∼0"1. The blueshifted and redshifted [Ne…
X-ray emission of Seyfert 2 galaxy MCG-01-24-12
Bianchi, S.; Dadina, M.; Braito, V. +7 more
We present a detailed X-ray spectral analysis of the nearby Seyfert 2 galaxy MCG-01-24-12 based on a multi-epoch data set. Data were obtained with different X-ray satellites, namely XMM-Newton, NuSTAR, Swift, and Chandra, and cover different time intervals, from a few days to years. From 2006 to 2013 the source had a 2-10 keV flux of ∼1.5 × 10
The G 305 Star-forming Region. II. Irregular Variable Stars
Bayo, A.; Kounkel, Marina; Minniti, Dante +11 more
We present a catalog of 167 newly discovered, irregular variables spanning a ~7 deg2 area that encompasses the G 305 star-forming complex, one of the most luminous giant H II regions in the Galaxy. We aim to unveil and characterize the young stellar object (YSO) population of the region by analyzing the Ks-band variability an…
Trends and characteristics of high-frequency type II bursts detected by CALLISTO spectrometers
Kumari, A.; Monstein, C.; Sasikumar Raja, K. +2 more
Solar radio type II bursts serve as early indicators of incoming geo-effective space weather events such as coronal mass ejections (CMEs). In order to investigate the origin of high-frequency type II bursts (HF type II bursts), we have identified 51 of them (among 180 type II bursts from SWPC reports) that are observed by ground-based Compound Ast…
Photometric and kinematical analysis of Koposov 12 and Koposov 43 open clusters
Elsanhoury, W. H.
We present a photometric and kinematical analysis of two poorly studied open clusters, Koposov 12 (FSR 802) and Koposov 43 (FSR 848), by using cross-matched data from PPMXL and Gaia DR2 catalogs. We used astrometric parameters to identify 285 and 310 cluster members for Koposov 12 and Koposov 43, respectively. Using the extracted member candidates…
Stellar X-rays and magnetic activity in 3D MHD coronal models
Peter, H.; Zhuleku, J.; Warnecke, J.
Context. Observations suggest a power-law relation between the coronal emission in X-rays, LX, and the total (unsigned) magnetic flux at the stellar surface, Φ. The physics basis for this relation is poorly understood.
Aims: We use three-dimensional (3D) magnetohydrodynamics (MHD) numerical models of the coronae above active region…